In many chairs with a backrest as well as chairs for office work, the backrest can be inclined rearwardly. There is known a chair of this type so constructed that a backrest is mounted inclinably on a support base supporting a seat, with a resiliently urging mechanism resiliently urging the backrest forwardly. There is also known another chair so constructed that a seat and a backrest form an integral body and the front end of the seat is supported inclinably on the front end of a support base, with a resiliently urging mechanism resiliently urging the seat and the backrest in a required direction.
In these chairs, when a rearwardly directed pressure is applied to the backrest, only the backrest or both the backrest and the seat are rearwardly inclined against the urging force of the above-mentioned resiliently urging mechanism, so that the chair can take a rest position.
With this arrangement, however, there is a problem that when the backrest is inclined rearwardly, the center of gravity of the user is greatly shifted rearwardly relative to a support base provided on a leg, so that the user is likely to fall down rearwardly.
On the other hand, there are known chairs in which the seat can be shifted forwardly when the backrest is inclined rearwardly. Among such chairs are chairs used for buses and trains, in which the seat is supported on a support base slidably in forward and rearward directions, and the lower end of the frame of the backrest is mounted pivotally on the rear end of the above-mentioned seat, and the intermediate portion of the backrest frame is mounted on the above-mentioned support base pivotally or both pivotally and slidably up and down.
In this type of chair, when the backrest is inclined, the position of the occupant is not greatly shifted rearwardly. With this arrangement, however, unless the relatively upper portion of the backrest is pushed rearwardly, the backrest cannot be pivoted. This poses a problem that when the user pushes the backrest with his whole back to take a rest position, the movement of his back does not coincide with that of the backrest, so that he feels uncomfortable.
This invention has been proposed in view of these problems encountered in the prior art, and its object is to provide a chair having a backrest, in which the seat is shifted forwardly upon rearward inclination of the backrest, thereby to prevent the chair from falling down rearwardly, and in which the backrest can be inclined rearwardly by pushing any part of the backrest rearwardly without causing uncomfortable feeling to the occupant pushing the backrest.